Untimely disconnect of external disk drive, now I cannot mount it
Many times I have inadvertently disconnected an external drive before "ejecting" it, a procedure that evokes a system warning but upon restart a result without consequence. The external drive remounts perfectly when reconnected. Now for the first time I find I cannot remount a disk that I inadvertently disconnected before ejecting it. Attempt at using palliatives such as "Disk Utilities" to
This disk is actually a second of two logical partitions on a single external disk. I don't see how this can make a difference, except in this case the first partition on the same external hard disk re-mounted without flaw.
I tried using Disk Utility to Verify and Repair volume. But Disk Utility responds "... can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files." There is now indication how I can use Disk Utility to do this. So what is to be done?
For example, I have routinely backed up my main internal disk to this external hard disk via Time Machine. But the destination for the Time Machine backup of my main computer is this very same external disk partition that I cannot remount! So it seems to me that, to "back up my files," would require me to read and write from this now disabled partition. I tried using TechTools in "recover files" mode without result since it also seems to assume that the target disk is mounted. Might I need to resort to "terminal" mode to discover how to remount this delinquent partition, or at least to copy files from the crippled volume?
Any ideas?
iMac (21.5-inch Mid 2011), Other OS, OSX Maverick 10.9.4